Internal Safety Valves

Automatic shut-off protection inside the tank or in-line.

What It Is & How It Works

Internal safety valves are shut-off devices installed inside the tank shell or in-line on fill, discharge, or product nozzles. They provide automatic or emergency closure of the pipeline connection at the tank wall, preventing product flow during burning events. They provide the fundamental safety protection requirement that every tank needs to isolate its contents from connected piping under fire conditions.

The valve body mounts inside the tank with the seat at the nozzle flange, and a closure element seals against the seat to stop flow. Fusible-link models hold the valve open with a heat-sensitive element that melts during fire exposure, allowing a spring or counterweight to drive the closure element shut and isolate tank contents from exposed piping.

Internal safety valves install through standard tank shell nozzles and require no external piping modifications. Sizing depends on the nozzle diameter, maximum flow rate, and the specific gravity of the stored product. Because the valve sits entirely inside the tank, it remains protected from external mechanical damage, weather exposure, and fire exposure.

Manual vs. Hydraulic Actuated Fusible-Link Internal Safety Valves

The manually actuated valve is held open by a chain and fusible link that automatically releases and closes upon fire exposure at 212°F, with no remote operation capability. The hydraulically actuated valve fails closed on loss of pressure and integrates with emergency shutdown systems for remote operation on pressurized services such as LPG and anhydrous ammonia. Both use spring-loaded automatic closure, but the manual valve relies solely on heat while the hydraulic valve can be shut remotely from a safe location at any time.

When to Specify Internal Safety Valves

Internal safety valves are specified when a tank requires automatic or emergency shut-off at the tank wall connection under burning environmental conditions.

LPG Sphere and Bullet Tank Storage Installed at all liquid and vapor outlet connections under NFPA 58 and API 2510 to provide automatic shutoff in the event of external piping failure, vehicle drive-away during loading, or fire exposure.
Anhydrous Ammonia Storage and Transfer Required under OSHA PSM regulations and ANSI K61.1 at all liquid withdrawal connections to ensure immediate shutoff of any toxic release caused by piping failure or impact damage.
Flammable and Combustible Liquid Storage Tanks Specified on above ground storage tanks handling flammable liquids such as gasoline, diesel, and fuel oil under NFPA 30 to ensure product flow can be stopped at the tank in the event of downstream piping failure.
Transportation Loading and Unloading Terminals Required under DOT 49 CFR Part 178 and NFPA 58 at all transfer connections on pressurized transport vessels to protect against catastrophic release in the event of a vehicle drive-away while still connected.
Cryogenic and Refrigerated Storage Vessels Specified on liquid oxygen, nitrogen, ethylene, and LNG storage tanks under NFPA 59A and CGA standards to ensure reliable isolation capability across a wide temperature range independent of external piping integrity.

Why It Excels

Why Shand & Jurs Internal Safety Valves Excel

Tanks Requiring Passive Fire Protection Without Remote Control Systems

Manually actuated fusible link models close automatically when ambient temperature at the nozzle reaches the link's rated melting point, isolating the tank before external piping integrity is compromised by fire exposure, requiring no power, control system, or operator intervention.

Facilities Requiring Remote Emergency Shutoff and ESD Integration

Hydraulically actuated models fail closed automatically upon loss of operating pressure and integrate directly with facility emergency shutdown systems, allowing operators to isolate the tank remotely from a safe location during an emergency.

Installations with Limited Space for External Emergency Valves

Because the entire valve body sits inside the tank, both manual and hydraulic internal safety valves require no additional external piping space, actuators, or mounting brackets on the tank shell exterior.

Facilities Operating Without Continuous Power or Control Systems

Manually actuated fusible link models use purely mechanical actuation ensuring the valve operates reliably during power failures, control system outages, and communication losses without any dependency on utilities or instrumentation.

Multi-Product Terminals with Varied Nozzle Configurations

Both manual and hydraulic models are available in sizes from 2 to 14 inches and in carbon steel, stainless steel, and aluminum construction to match each tank's nozzle diameter, stored product, and operating temperature range.

Manual vs Hydraulically Actuated Fusible-Link Internal Safety Valves — Selection Guide

Attribute	Manual (Fusible Link)	Hydraulically Actuated (Fusible-Link)
Primary Function	Fire-case isolation via automatic closure when heat exposure melts the fusible link	Remote and emergency shutoff with automatic fail-closed closure upon loss of hydraulic pressure
Actuation Method	Heat-sensitive fusible link releases the spring-loaded closure element	Hydraulic pressure holds valve open against spring force; loss of pressure allows spring to close valve
Trigger Condition	Ambient temperature at the nozzle reaches the fusible link's rated melting point, typically 212°F	Loss of hydraulic operating pressure from control line failure, ESD activation, or operator command
Remote Method	No remote capability; valve responds only to heat at the valve location	Fully remote operable from control panel or ESD station at any safe distance
Reset Method	Manual; fusible link must be replaced and valve manually reset before returning to service	Hydraulic pressure restored to control line; valve reopens remotely without physical access to valve
Regulatory Driver	NFPA 30, NFPA 58 fire-case piping isolation requirements	NFPA 58, API 2510, OSHA PSM remote shutoff and ESD requirements
Recommendation	Specify where passive fire protection is the primary concern and remote operation or ESD integration is not required	Specify on all pressurized vessels where remote emergency closure, ESD integration, or regulatory remote shutoff compliance is required

What to Consider Alongside Internal Safety Valves

Precise Level-based Overfill Prevention With Alarm Notification You need electronic high-level detection with audible/visual alarms and control system integration rather than a mechanical shut-off. See L&J Technologies level alarm probes and Clairvoyance.
Hydraulic Operator A dedicated hydraulic operator is required to remotely open and close hydraulically actuated internal safety valves, providing the means to operate the valve from a safe distance during normal operations and emergencies.
Pressure or Vacuum Breathing Protection You need to control tank breathing during normal thermal and pumping cycles rather than isolate a pipeline connection. See Conservation Vents & Seals.
Layered Overfill Prevention Per API 2350 L&J Technologies electronic high-level alarm probes to provide independent mechanical and electronic overfill prevention layers, satisfying Category 3 and Category 4 overfill prevention system requirements.
Complete Tank Protection Assembly Pair internal safety valves with conservation vents for breathing protection, flame arresters for ignition prevention, and gauge hatches for vapor-tight access to create a fully protected tank that addresses all regulatory requirements at every opening and nozzle. See Conservation Vents & Seals, Flame & Detonation Arresters, and Gauge Hatches & Manway Covers.

Featured Products

96311 — Manual Internal Safety Valve

Manually operated internal safety valve held open by a chain and fusible link that automatically releases and spring-closes upon fire exposure at 212°F, providing passive fire-case isolation at tank nozzles wherever flammable or hazardous liquids are stored or transferred.

96330 — Hydraulically Actuated Internal Safety Valve

Hydraulically actuated internal safety shutoff and operating valve that automatically fails closed upon loss of hydraulic pressure, providing remote emergency isolation and bidirectional shutoff on pressurized tanks and manifold lines handling LP-Gas, anhydrous ammonia, and similar products.

96330I — Hydraulically Actuated Internal Safety Valve with Visual Indicator

Incorporates all the features of the 96330 with the addition of an integral position indicator physically attached to the valve mechanism, providing continuous visual confirmation of true valve position for operations and compliance verification.